Re: Origin of feathers

["Jaime Headden" <jaemei@hotmail.com>]

I wrote:
<<This is true for modern avians, and even Archie and *Rahonavis* 
possessed ridges on the ulna, but this purpose is to anchor the 
feathers, to give them support when air pressure worked against them, as 
in flight, or in animals of direct association with volant birds 
(secondarily flightless, in other words).>>

Matt wrote:
<Hold up. Archaeopteryx has no such ulnar papillae as shown 
conclusively by Wellnhofer. The ulna of Archaeopteryx is relatively 
thin and narrow compared to "higher" birds such as enantiornithines and 
ornithurines.>

  I did say "ridge" and not "papillae"; My meaning was that the presence 
of a ridge meant more firmly anchored feathers than a rounded ulna would 
seem to support, and as you went on to say,

<However, in many ratites which anchor reduced but present remiges on 
their forelimbs, no such ridge (or papillae) is present.  
     The purpose of the ulnar papillae is first and foremost a strong 
articulating surface for flight remiges so the bird can flap its wings 
without having to worry about the feathers falling out. The lack of 
such papillae is not evidence that a particular bird did not fly, for 
many birds lack ulnar papillae (for example, _Foro panarium_).>

Jaime A. Headden

"You must be so lonely...."
                 -- Frank Black

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com